According to the Ideal Gas Law, the volume of a gas is inversely proportional to its pressure, assuming the temperature and amount of gas remain constant. This is expressed by the following equation:
PV = nRT
where P is the pressure of the gas, V is the volume of the gas, n is the number of moles of gas, R is the ideal gas constant, and T is the temperature of the gas in Kelvin.
If we keep the number of moles of gas, the temperature, and the gas constant (R) constant, and double the pressure (P), the volume (V) of the gas will be reduced to half its original value.
This relationship is known as Boyle's Law, which states that the volume of a gas is inversely proportional to its pressure at a constant temperature. Therefore, if the pressure of a gas is doubled while everything else is held constant, the volume of the gas will be halved.